The disadvantage with boon stripping would be either to lose dps because the weapons for this are condition focused or that you infict conditions on yourself to do so and buffing is not something that necro can excell at since it does not have many, and no real potent capabilities to do so. It's can hower very well infict conditions when focused on it. Even in a power build it can pump out a lot of chill, and it is very good at inflicting vulnerability.